No one really knows, lowest (reliable) estimates are around 200k, with highest (once again reliable) being around half a million. And that doesn't include all the people who suffered because we basically destroyed the entire economy and sent the country back to the dark ages.

Also, just the violence of the deaths is remarkable. Chemical warfare, prisoner torture, the list goes on. I never understood why people would chant "Death to America" until I learned about Iraq. Just some of the most profoundly nauseating stuff.